Mr Bryson claimed that from the beginning of his private message exchanges with the Twitter account of Thomas G O'Hara, he worked on the assumption that it was Sinn Fein MLA Daithi McKay, who has since resigned.

"I knew all along this was not Thomas O'Hara," he said. "I have no idea who Thomas O'Hara is. I never met or spoke to him before in my life.

"'I'm sure it was Daithi McKay. I still believe the person I was corresponding with was Daithi McKay. Sinn Fein were wrong to suspend Thomas O'Hara. He was not involved."

Last night, the loyalist denied he leaked information that led to Daithi McKay's resignation - and called for a full public inquiry into the affair.

"I wish to place on record that I was, in no shape or form, the leak of this back channel," he said.

Mr O'Hara and Mr McKay are alleged to have coached Mr Bryson for his appearance at Stormont's National Management Agency (Nama) inquiry last year.

Leaked tweets show exchanges between the three before Mr Bryson testified at the finance committee inquiry, chaired by Mr McKay, into the £1.2bn sale of Nama's property loan portfolio in Northern Ireland.

The messages appear to show how Mr McKay and Mr O'Hara instructed Mr Bryson on what to say before he gave evidence into the probe about the sale of Nama's Northern Ireland loan book.

Last July, independent TD Mick Wallace claimed that £7m in an offshore bank account linked to the deal had been earmarked for a Northern Ireland politician.

Mr Bryson told the committee that former DUP leader Peter Robinson was to receive a payment upon its completion - claims that the former First Minister has consistently denied.

Just hours after the leaked Twitter messages were made public on Thursday, Mr McKay resigned as an MLA and apologised. Mr O'Hara was suspended from the party yesterday.

Mr Bryson has claimed that others "higher up in Sinn Fein than Daithi" were aware of the correspondence. A reference within the messages was made to Finance Minister Mairtin O'Muilleoir, who at the time was a member of the finance committee.

In one message, sent the day before the committee was to discuss whether Mr Bryson would give evidence in public or private, Mr Bryson offered to email his presentation to Mr O'Hara.

Mr O'Hara replied: "I'm just trying to establish what Mairtin or someone can jump upon and say 'there's no way we can turn him away, this is credible, relevant and in the public interest'."

According to the messages, five days before the inquiry hearing Mr O'Hara gave Mr Bryson an email address to send his planned opening statement to.

Mr O'Hara then advised Mr Bryson to "play it cool and keep it factual" while addressing the committee as "DUP want it to be a shouting match and then they could get meeting postponed".

The messages began on September 17, 2015, when Mr McKay sent a direct message to Mr Bryson telling him to follow a Twitter account in the name of Thomas O'Hara, a fellow Sinn Fein member.

Mr Bryson says he stood by the testimony he gave to the Stormont inquiry.